The present invention relates to carburetors for internal combustion engines, and more particularly to a carburetor of the type in which a heating device is provided to heat the fuel and/or air up to a predetermined temperature so as to accelerate the ignition of the fuel and air mixture.
Conventional heating devices of this kind are generally classified into a heating device having an electric resistance element and another type of heating device having a heat exchanger leading therein exhaust gases from an internal combustion engine. With the heating device of the former type, thermal energy of the electric resistance element is very influenced by the increase or decrease of the flow quantity of the fuel and/or air to cause unstable changing of the mixing rate of the fuel and air. It is, therefore, required that an electric control device is adapted to the heating device to ensure the thermal energy of the resistance element in accordance with variation of the flow quantity of the fuel and air. On the other hand, with the heating device of the latter type, sufficient thermal energy may not be obtained by the heat exchanger immediately after start of the engine. It is also required that the exhaust gas from the engine is heated to ensure sufficient thermal energy in accordance with the flow quantity of the fuel and air.